This is a pretty good image Paul, you clearly have the material to work with, once you have all your teething problems sorted you will be producing corkers for sure
Out of interest (I think I may have asked this already?) if you get perfect polar alignment have you tried going unguided? That EM400 should be capable of some pretty schmick tracking without guiding? Look at what my NJP can do for example:
http://upload.pbase.com/strongmanmik...31590/original
This unguided sub was taken in average seeing under solid light pollution from inner Canberra and if I recall, a moon in the sky too, hence the dust donuts? There is a tiny bit of elongation (more noticable in some stars than others though) most probably due to filter tilt mostly but man, at a pinch I would take this any day.
here is 4min unguided and magnified 200X:
http://www.pbase.com/strongmanmike20...88817/original
When turned on, and in good seeing the autoguiding corrections average only 0.1 pix or less at 2.3"/pix or +/- 0.23". I only ever piggyback guide too and this nearly always translates into round stars, so I am bewildered as to why you are having so much trouble with the EM400
I feel for ya man, very fustrating
Actually I have never had this NJP permanently setup on a rock solid permanent pier but should I do so one day and go for really acurate polar alignment it will be very much fun to turn off autoguiding particularly on on nights of poorer seeing
Have you ever got pefect polar alignment after some serious drift alignmnet and checked your native tracking quality? It may be worth trying.
Mike